Closure cap provided with anti-twisting

ABSTRACT

A pressure cap ( 111 ) for openings in tanks, in particular in automobile radiators, has an outer cap component ( 110 ) which is provided with a locking element ( 113 ) that can be connected to the tank&#39;s neck, and provided with a handling element ( 112 ) rotatably mounted in relation to said locking element, and furthermore provided with a coupling insert ( 180 ) which is anti-rotationally mounted in the handling element ( 112 ) and which can be axially engaged in and disengaged from the locking element ( 113 ) to allow a releasably non-rotational connection between the locking element and the handling element, and which furthermore is provided with a valve assembly ( 115 ) containing a valve body ( 117 ) that can be axially moved back and forth, for releasing and blocking flow connections between the inside and the outside of the tank depending on the pressure prevailing inside the tank. To create an anti-rotation means directly governed by and in time and sequence with the conditions prevailing inside the tank, it is provided that the engaging and disengaging movement of the coupling insert ( 180 ) is derived from the pressure-dependent axial movement of the valve body ( 117 ) of the valve assembly ( 115 ).

[0001] The present invention relates to a pressure cap for openings intanks, in particular in automobile radiators, according to the genericpart of claim 1.

[0002] In such pressure caps for openings in tanks, in particular inautomobile radiators, which are known from WO 95/32904, the movement ofthe coupling insert between the handling element and the locking elementof the outer cap component is controlled by the temperature via a memoryspring. In such cases, the memory spring lies inside the inner capcomponent on the side of the valve assembly that faces away from theinside of the tank. It was found that this remote arrangement of thememory spring causes problems and delays in measuring the temperatureprevailing inside the tank, which leads to less than satisfactoryresults in activating and deactivating the anti-rotation means.

[0003] The object of the present invention is to improve a pressure capof the above kind for openings in tanks, in particular in automobileradiators, such that an anti-rotation means can be created which isdirectly governed by and in time and sequence with the conditionsprevailing inside the tank.

[0004] To achieve this object, the characteristics named in claim 1 areprovided for a pressure cap for openings in tanks, in particular inautomobile radiators.

[0005] Thus, the anti-rotation means can be activated and deactivatedsubstantially without time delay and directly by deriving the movementdirectly from the valve body depending on the pressure prevailing insidethe tank. Since the pressure inside the tank directly affects therespective valve body of the valve assembly, there is also a directeffect on the activation and deactivation of the anti-rotation means.

[0006] In one preferred embodiment of the present invention, thecharacteristics named in one or more of claims 2 to 7 are provided. Inthis preferred embodiment, the anti-rotation means is activated bytransmitting the movement via a compression spring, while the return toits deactivated position is accomplished by a combination of compressionspring and traction mechanism.

[0007] In another preferred embodiment of the present invention, thecharacteristics named in one or more of claims 8 to 19 are provided. Inthis preferred embodiment, the anti-rotation means is activated by arigid movement transmission from the valve body to the coupling insert,while the return to its deactivated non-rotational position isaccomplished via a counter-compression spring.

[0008] Further details of the invention are provided in the followingdescription in which the invention is explained in detail with referenceto the drawings, where:

[0009]FIG. 1 is a longitudinal section through a pressure cap for anautomobile radiator with a pressure-relief/vacuum valve assembly and ananti-rotation means in closed, i.e. non-activated initial position,according to a first preferred embodiment of the present invention;

[0010]FIG. 2 is a view that corresponds to that in FIG. 1, but showing aposition while pressure is building up inside the tank;

[0011]FIG. 3 is a view that corresponds to that in FIG. 1, but showing aposition after the pressure inside the tank exceeds the first thresholdvalue but before it reaches a second threshold value;

[0012]FIG. 4 is a view that corresponds to that in FIG. 1, but showing aposition after the pressure inside the tank exceeds a third thresholdvalue which constitutes the safety limit;

[0013]FIG. 5 is a view that corresponds to that in FIG. 1, but showing aposition after normal pressure is reached inside the tank and before theanti-rotation means is returned to its deactivated position;

[0014]FIG. 6 is a longitudinal view of a pressure cap for an automobileradiator with a pressure-relief/vacuum valve assembly in closed initialposition and with an engaged non-rotation means according to a secondpreferred embodiment of the present invention;

[0015]FIG. 7 shows the pressure cap as in FIG. 6 in a position at aslight overpressure inside the tank and with the anti-rotation meansdeactivated;

[0016]FIG. 8 shows the pressure cap as in FIG. 6 in a position after thepressure inside the tank exceeds a first threshold value;

[0017]FIG. 9 shows the pressure cap as in FIG. 6 in a position after thepressure inside the tank exceeds a second threshold value and dynamicpressure prevails;

[0018]FIG. 10 shows the pressure cap as in FIG. 6 when the pressureinside the tank has exceeded a third threshold value which constitutesthe safety limit.

[0019] Pressure cap 111, 211 shown in the drawings by example of twoembodiments for a tank such as an automobile radiator has an outer capcomponent 110, 210 which is provided with a handling, element orhandling means 112, 212 to whose locking element 113, 213 (shown here asa screw-on element) an inner cap component 114, 214 with apressure-relief/vacuum valve assembly 115, 215 is rotatably suspended.When in use, the pressure cap 111, 211 is fixed or screwed to a radiatorneck (not shown). Inner cap component 114, 214 protrudes from theradiator neck into the inside of the radiator. An O ring 116, 216 sealsthe inner cap component 114, 214 against the wall of the radiator. Inthe two-piece outer cap component 110, 210, the cap-like handling means112, 212 is axially fixed to the screw-on element 113, 213, although itcan be rotated in circumferential direction. When there is normalpressure inside the radiator, this rotatability is blocked by an axiallymovable coupling insert 180, 280 for screwing and unscrewing pressurecap 111, 211.

[0020] In the embodiment shown in FIG. 1 to 5, the pressure-relief partof the valve assembly 115 is designed in two steps. In a firstoverpressure step, it has the function of preventing the radiator fromboiling dry, and in a second overpressure step it prevents damage to theradiator system due to excessive overpressure. The pressure-relief partof the valve assembly 115 is provided with a single valve body 117,which is axially movable inside the inner cap component 114 between twoend positions. Valve body 117 has a contoured ring seal 118 with anaxially acting sealing surface arrangement 120 and a radially actingsealing surface arrangement 121. Valve body 117 is axially biased towardthe inside of the tank by means of a compression spring 122 which issupported by the inner cap component 114.

[0021] Inner cap component 114 is designed in two parts, namely an innerelement 125 and an outer main element 126 which is suspended in thescrew-on element 113 of outer cap component 110 and in which the fixedinner element 125 is sealed. Inner element 125 has the approximate shapeof a hood with an axial opening in the hood floor 128 by whose insideone end of compression spring 122 is supported. At approximately thelevel of the lower end of the outer cap component 110, the outercircumference of inner cap component 114 is provided with escapeopenings 129. Between the inner element 125 and the main element 126, anO ring 124 is provided to ensure a tight connection.

[0022] Floor 131 of main element 126 of inner cap component 114 has acoaxial flow-through opening 132 which forms a connection between theinside of the tank and the inside of the interior cap component 114.Flow-through opening 132 is coaxially surrounded by an annular lug 133whose free annular face forms a sealing seat 134 for the axial sealingsurface arrangement 120 of contoured ring seal 118 of valve body 117. Anannular space 136 remains between the outer circumference of annular lug133 and the inner circumference of main element 126. Above that annularspace 136, between the lower annular face of inner element 125 and arecess in the main element 126 of inner cap component 114, an annularinsert is accommodated which contains a U shaped throttle channel 139 orforms such a channel with its adjacent components. In the embodimentshown, the U shaped throttle channel 139 is provided in a place on thecircumference of inner cap component 114. Throttle channel 139 has tworadial channel parts arranged at an axial distance: 141 (adjacent toinner element 125) and 142 (adjacent to the recess in main element 126),which are connected by an axial channel part 143 located between theassociated inner circumference section of main element 126 and theassociated outer circumference section of annular insert 138. Here, thechannel parts 141, 142 and 143 are formed by radial or axial grooves cutinto the annular insert 138.

[0023] One-part valve body 117 has a radially stepped main part 146 inaxial direction, which carries the contoured ring seal 118, and onwhich—facing away from the contoured ring seal 118—sits a guidanceelement 147 which is hollow cylindrical and engages in the hollowcoupling insert 180. Compression spring 122 is supported on a radialouter shoulder of main part 146 of valve body 117.

[0024] On the inner surface of the stepped outer circumference of valvebody 117, the contoured ring seal 118 is fastened. Seen in crosssection, the axial sealing surface arrangement 120 of contoured ringseal 118 is vault-shaped and has a radially outer sealing surface 151, aradially central sealing surface 152 and a radially inner sealingsurface 153. The radially inner sealing surface 153 interacts with avacuum valve body 171, which will be described below, while the radiallycentral sealing surface 152 in rest position bears on the sealing seat134 of inner cap component 114 and the radially outer sealing surface151 lies on the floor of annular space 136. On the other hand, theradial sealing surface arrangement 121 has two sealing surfaces 156 and157 arranged at a certain axial distance, between which a cut-out 158 isprovided. The upper sealing surface 156 as well as the lower sealingsurface 157, which turns into the radially outer sealing surface 151,are sealingly adjoining the inner wall 161 which is formed as a sealingseat, and/or 162 of main element 126 of interior cap component 114 orannular insert 138.

[0025] One inner end of guidance element 147 sits on the outer surfaceof the inside shoulder of valve body 117, while its other end extendsinto the centered through-hole of coupling insert 180. Coupling insert180 and guidance element 147 are mutually rotatable and can slideaxially toward each other. As FIG. 1 shows, the axial slidability islimited by the adjoining shoulders 181, 182 such that guidance element147 and coupling insert 180 always engage each other. Guidance element147 is designed as a sleeve whose outer circumference at the inner endfacing valve body 117 is stepped to form contact shoulders for an axialspring coupling means. The spring coupling means has a first innerpressure coil spring 183 which is arranged with bias between couplinginsert 180 and guidance element 147, and a second outer pressure coilspring 184 whose one end is supported by guidance element 147 and whoseother end is supported by inner element 125 of inner cap component 114.These two pressure coil springs 183 and 184 are surrounded by pressurecoil spring 122 which acts upon valve body 117.

[0026] The axially slideable coupling insert 180, whose lower end, whichoverlaps guidance element 147, passes through a central through-hole ofinner element 125 of inner cap component 114, has an outer end with alarger diameter. As shown in FIG. 1, this end lies within a recess 186of a radial flange 187 of screw-on element 113 and within a centeredring flange 188 which protrudes axially toward the inside. Couplinginsert 180 is non-rotationally connected to the axial flange 188 on thehandling means 112, for example through intermeshing peripheral teeth.In the initial position shown in FIG. 1, the coupling insert 180 is alsonon-rotationally connected with the radial flange 187 of screw-onelement 113, also via peripherally and axially extending tootharrangements (not shown). In this manner, the handling means 112 and thescrew-on element 113 are non-rotatably connected with each other incircumferential direction, such that the pressure cap 111 can be screwedon and off the neck (not shown) of a tank with handling means 112.

[0027] In the centre of valve body 117, an opening 166 is provided whichis on the side facing the inside of the radiator is closed by the vacuumvalve body 171 of valve assembly 115. Main part 172 of vacuum valve body171 protrudes through central opening 166, and its end section is actedupon by a compression spring 167 which is supported at one end by ashoulder of main part 172 and at the other end by the outer surface ofthe inner shoulder of valve body 117. In this manner, the annularsealing seat 173 of vacuum valve body 171 is sealingly adjoining theradially inner sealing surface 153 of the axial sealing surfacearrangement 120 of contoured ring seal 118 of valve body 117.

[0028] In the rest position (initial operating position) shown in FIG.1, when there is no overpressure inside the tank yet, any flowconnection between the inside and the outside of the tank is closed bythe fact that all sealing surfaces 151 to 153 of the axial sealingsurface arrangement 120 of contoured seal 118 of valve body 117sealingly adjoin the corresponding sealing seats 136, 134, 173 of innercap component 114 or vacuum valve body 171. In other words, at contouredring seal118 of valve body 117 as well as on the underside of vacuumvalve body 171, the normal (ambient) pressure in the form of the aircushion above the liquid coolant prevails through flow-through opening132.

[0029] When the pressure inside the tank rises to a certain level abovenormal pressure, but below a first threshold, the unscrew protectionmeans of pressure cap 111 is activated. As shown in FIG. 2, valve body117 is moved upward, such that the contoured ring seal 118 with itscentral sealing surface 152 is lifted off sealing seat 134. Thus, theeffective surface acted upon by overpressure, which until then wasformed only by the underside of vacuum valve body 171, is enlarged bythe inner axial surface of the contoured ring seal 118. This enlargedeffective surface means that a greater force is acting upon valve body117 while the pressure remains the same, resulting in greater lift forthe valve body. Due to the lift movement of valve body 117, whichhowever does not yet open throttle channel 139, against the effect ofthe first pressure coil spring 183 and the second pressure coil spring184, the guidance element 147 is initially displaced axially in relationto coupling insert 180. Since this lift movement biases the firstpressure coil spring 183 which is supported by coupling insert 180,coupling insert 180 is axially displaced. This axial outward movement ofcoupling insert 180 in the direction of Arrow A and up to an inner stopon the underside of handling means 112 causes the end of coupling insert180 with the larger outer diameter to disengage from the teeth onscrew-on element 113. This disengagement of coupling insert 180 has theeffect that the handling means 112 idles in relation to screw-on element113, such that above a certain defined overpressure (in this case, forexample, 0.3 bar), pressure cap 111 can no longer be unscrewed.

[0030] If the pressure inside the tank increases further, i.e. above thepredetermined first threshold value (e.g. 1.4 bar), valve assembly 115of pressure cap 111 reaches the operating state shown in FIG. 3according to which valve body 117 continues to lift against the effectof its compression spring 122, and the contoured ring seal 118 movesinto the range of annular insert 138, such that the two radial sealingsurfaces 156 and 157 of the radial sealing surface arrangement 121 ofcontoured ring seat 118 of valve body 117 are below/above the radialchannel parts 141 and 142 and thus open throttle channel 139 on bothsides. In this state, in which the unscrew protection means remainsactivated, an equilibrium has occurred between the effect of thepressure inside the tank and the counter effect of compression spring122. Thus, the first flow connection between the inside and the outsideof the tank is open, which leads from flow-through opening 132 via theU-shaped throttle channel 139 to the escape openings 129. This meansthat air can flow outside from the air cushion above the liquid coolantand compensate or reduce the overpressure. If this reduces theoverpressure below the first threshold value, valve body 117 is againmoved to sealingly adjoin the axial sealing seat 134 of inner capcomponent 114.

[0031] If on the other hand, the pressure inside the tank continues torise during or after the escape of the air cushion, and if this causesliquid coolant to reach the underside of contoured ring seal 118 andvacuum valve body 171, the fact that throttle channel 139 is very narrow(e.g. a cross section measuring only a few hundredths of a millimeter),causes the coolant to back-up at the entrance to the lower radialchannel part 142 of throttle channel 139, and therefore causes dynamicpressure on the full-surface undersides of contoured ring seal 118 andvacuum valve body 171. This dynamic pressure leads to an axial movementof valve body 117 against the effect of compression spring 122, suchthat in this state (e.g. of 1.4 bar), throttle channel 139 is closedagain (in a manner not shown) at upper channel part 141 by the upperradial sealing surface 156 of contoured ring seal 118. The unscrewprotection means continues to be activated. This prevents the dischargeof liquid coolant. If the pressure inside the tank is reduces throughcooling and the liquid coolant is returned, valve body 117 can also bereturned under the effect of its compression spring 122, such thatthrottle channel 139 opens again and the pressure can be reducedfurther.

[0032] If, on the other hand, the pressure inside the tank continues torise, valve body 117 is lifted further against the action of compressionspring 122 when an upper (safety) threshold (e.g. of 2 bar) is exceeded,such that axial escape channels 169—situated in certain circumferentialsections in the wall of annular insert 138 and of the inner element 125of inner cap component 114—are opened which are connected to escapeopening 129 and thus with the outside of the tank (FIG. 4). In thatstate, the upper channel part 141 remains closed as before. This upperend position of valve body 117 is limited by the compressed compressionsprings 122, 183 and 184. The unscrew protection means remainsactivated. This means that the said overpressure can be reduced via asecond flow connection, after which valve body 117 can be returnedthrough the various operating states by compression spring 122, as shownin FIG. 5.

[0033]FIG. 5 also shows a possible short-term state of the unscrewprotection means when valve body 117 has returned to its initialposition and when the handling means 112 was rotated while theactivation of the unscrew protection means was activated. In that case,it could have happened that the teeth of coupling insert 180 are notexactly above the tooth spaces of screw-on element 113. To return theunscrew protection means from its activated state into its deactivatedstate, as shown in FIG. 1, it is enough to give handling means 112 ashort turn, which has the effect that the second pressure coil spring184, which is under considerable bias, moves guidance element 147 downagainst the direction indicated by Arrow A. This releases the innerfirst compression spring 183, while the outer ring shoulder 181 ofguidance element 147 adjoins the inner ring shoulder 182 of couplinginsert 180 and carries the latter along against the direction indicatedby Arrow A, such that the coupling connection between handling means 112and screw-on element 113 engages again and becomes effective. Thus, theexact operating position shown in FIG. 1 is reached, and pressure cap111 can be safely unscrewed from the neck of the radiator.

[0034] Valve assembly 115 assumes the initial position shown in FIG. 1when the pressure inside the radiator ranges between a vacuum thresholdand a very slight overpressure threshold of (in this case) less than 0.3bar. Such pressure conditions prevail, for example, in a vehicle thatwas parked for a long period, or when the vehicle is driven while thecoolant inside the radiator is sufficiently cooled by the headwindand/or the fan. If the vehicle is parked after a long drive, thepressure may rise inside the radiator causing the contents of theradiator (air, water or water vapour) to flow into valve assembly 115.If as a result of this after-heating effect, the coolant volume expandsso much that it exceeds the volume of the radiator, this necessarilyleads to a discharge of coolant. This undesirable effect is prevented inthe manner described above. If in this operating state, the pressure inthe cooling system continues to rise in an uncontrolled fashion,leakages and other detrimental effects due to excessive demands on theradiator and/or its hose connections must be prevented. Such effects areprevented through the second valve step as shown in FIG. 4, where theradiator pressure is limited to a predetermined safety threshold value.

[0035] If in case of an operating state as shown in FIG. 1 there is avacuum inside the radiator, and this vacuum falls below a predeterminedvacuum threshold value, the sealing seat 173 of vacuum valve body 171 islifted off the radially inside sealing surface 153 of contoured ringseal 118 of valve body 117 toward the inside of the radiator. Vacuumpressure valve 171 is lowered against the bias of compression spring167, such that a third flow connection (not shown) is opened between theinside and the outside of the radiator.

[0036] According to the embodiment shown in FIG. 6 to 10, thepressure-relief valve of valve assembly 215 is designed in two parts,and its function is to prevent (in a first overpressure step) theradiator from boiling dry, and (in a second overpressure step) to ensureprotection against damage to the radiator system due to excessiveoverpressure. The pressure-relief part of valve assembly 215 insideinner cap component 214 has a first valve body 217, a second valve body218, and a third valve body 219. The first valve body 217 is arranged inthe direction of the outside of the cap above the second valve body 218,while the third valve body 219 is accommodated coaxially within thesecond valve body 218.

[0037] The first valve body 217, which is designed in two parts, has aradially inner valve body part 265 approximately in the shape of a valvedisk, and a radially outer valve body part 266. These two parts overlapat the edge, whereby the radially inner part sits on the radially outervalve body part. On the side of the two valve body parts 265, 266 facingtoward the inside of the radiator, an annular membrane seal 221 isarranged which is provided with sealing surfaces facing axially inward.The radially outer stepped valve body part 266 of the first valve body217, on a side facing away from the inside of the radiator, is actedupon by a recoil spring 222 whose end facing away from the first valvebody 217 is supported by a spring plate 223 which in turn is supportedby inner cap component 214. The radially outer valve body part 226 ofthe first valve body 217 is biased in the direction of the inside of theradiator by means of recoil spring 222. Above the radially outer flatsealing edge 268 of membrane seal 221 sits the radially outer valve bodypart 226 on a first annular sealing seat 224 of the second valve body218. The radially inner valve body part 265 of first valve body 217 hasa central recess 237 whose annular limiting edge is surrounded by theinner part of membrane seal 221. Toward the inside of the radiator, thisradially inner U shaped sealing edge 267 of membrane seal 221 forms asealing surface for a vacuum valve 257 still to be described. On theside of the outer edge, the inner valve body part 265 bears on the inneredge of the radially outer valve body part 266 of first valve body 217.

[0038] The radially inner valve body part 265 is provided near itsradial outer edge with an axially protruding annular rim 269 on which aguidance sleeve 271 sits which is rotatable in relation to valve body265. The inner end of guidance sleeve 271 is curled over and overlapsannular rim 269 radially inside. Bearing on the other axial end ofguidance sleeve 271, which end is formed by single one-piece protrudingfingers 272, is coupling insert 280 under the effect of a compressionspring 281 which is supported on the inside of handling element 212 ofouter cap component 213. Coupling insert 280 has a disk 285 which isproved with axially downward extending finger-shaped claws whose crosssection corresponds to fingers 272 of guidance sleeve 271. When nopressure prevails inside the radiator, as shown in FIG. 6, fingers 272of guidance sleeve 271 as well as claws 282 of coupling insert 280engage in axial recesses 273 of locking element 210 of outer capcomponent 213. Furthermore, coupling insert disk 285 is provided axiallytoward the outside, i.e. facing away from claws 282, with protrudingclaws 283 which grip in positive connection between axially directedcircumferential teeth 284 of handling means 212. The inwardly directedclaws 282 lie on a radially inner ring, while the axiallyoutward-pointing claws 283 lie on a radially outer ring. In the initialor normal position shown in FIG. 6, a non-rotational connection existsvia coupling insert 280 between handling element 212 and locking element210 of outer cap component 213, such that pressure cap 211 can bescrewed to and unscrewed from the neck (not shown) of a radiator.

[0039] The one-piece second valve body 218 has a hood part 226 whosefree face is provided with the first sealing seat 224, and a concentricand hollow-cylindrical receptacle part 227 pointing from floor 228 ofhood part 226 to the inside of the radiator for the third valve body219. The outer circumferential side of floor 228 between hood part 226and receptacle part 227 is provided with a flange in whosecircumferential groove a second ring seal in the form of an O ring 231is accommodated. O ring 231 is provided with a second sealing seat 232which is formed by a collar rim on inner cap component 214. This collarring 232 is formed between a hollow-cylindrical upper part of inner capcomponent 214 (of greater inside diameter and accommodating the firstvalve body 217 and the hood part 226 of second valve body 218) and alower part of inner cap component 214 (of smaller inside diameter andsurrounding the receptacle part 227 of second valve body 218). In thislower section, the inner cap component 214 is provided with an axialopening 233. The radially outer valve body part 266 of the first valvebody 217 with sealing ring 268 of the first annular seal 221 is pressedby recoil seal 222 against the first sealing seat 224 of the secondvalve body 218, whose second ring seal 231 in turn is pressed againstthe second sealing seat 232 on inner cap component 214.

[0040] Located between the underside of first ring seal 221 and theupper side of floor 228 of the second valve body 218 is a cylindricalchamber 234 whose outer circumference is constant in axial directionbetween floor 228 and the underside of the first ring seal 221. Chamber234 is in communication in the middle via a hole 236 in floor 228 with arecess 237 in the second valve body 128. In a conical section arrangedat one free end of receptacle part 227, recess 237 enters the axialopening 233 of inner cap component 214. Between hole 236 and recess 237,the second valve body 218 is provided with a shoulder which is facingtoward the inside of the radiator and holding a third flat ring-shapedseal 239.

[0041] The third valve body 219, which is designed, for example, as arotational part with a stepped circumference in axial direction, isaccommodated with axial movement in recess 237 of second valve body 218.The third valve body 219 has a neck area 241 of smaller diameter whichis movable in hole 236 and within the third annular seal 239, and italso has a shoulder region 242 whose slanted shoulder forms a thirdannular seal 243 assigned to the third annular seal 239 on second valvebody 218, and it also has a cylindrical ventral region 244 which issupported in a manner not shown in detail by the inside wall of conicalsection 238 of the second valve body 218. For this purpose, withinrecess 237 a second compression spring 246 is provided whose one end issupported by a shoulder between the shoulder region 242 and the ventralregion 244. The third valve body 219 is biased in the direction of theinside of the radiator by the second compression spring 246. Between theventral region 244 of the third valve body 219 and in innercircumference of recess 237 of the second valve body 218 there is anannular gap 247 of very narrow width, i.e. only a few hundredth of amillimeter wide. As are hole 236 and chamber 234, the annular gap 247 ispart of a first flow connection 250 between the inside and the outsideof the cap. A second glow connection 251 bypasses the outercircumference of second valve body 218 (see FIG. 10).

[0042] In the centre of the radially inside valve body part 265 of firstvalve body 217 there is an opening 256, whose side facing the inside ofthe radiator is closed by vacuum valve body 257 of valve assembly 215.The main part 258 of vacuum valve body 257 protrudes through centralopening 256 in whose end section it is acted upon by a third compressionspring 259 which is supported at one end by a shoulder of main part 258and at the other end by the outer surface of the radially inner valvebody part 265. In this manner, the annular sealing seat 261 of vacuumvalve body 257 is sealingly adjoining the underside of the radiallyinner sealing edge 267 of the first ring seal 221 of the first valvebody 217. Sealing seat 261 of vacuum valve body 257 lies radially insidethe first sealing seat 224 of second valve body 218, while the latterlies radially outside the second sealing seat 232 of inner cap component214 and the latter in turn lies radially outside the third sealing seat243 on the third valve body 219. All sealing seats 224, 232, 243, 261point axially outward, while all sealing seats surfaces 221, 231, 239point axially inward.

[0043] In the initial operating position shown in FIG. 6, in which thepressure inside the radiator has not yet exceeded a first thresholdvalue, the first flow connection 250 is closed by the sealing contiguityof the first annular or membrane seal 221 of first valve body 217 to thefirst sealing seat 224 of second valve body 218. In other words, inchamber 234 and thus on the underside of the first ring seal 221 offirst valve body 217, the pressure inside the radiator in the form ofthe air cushion above the liquid coolant prevails through annular gap247. The second flow connection 251 along the outer circumference ofsecond valve body 218 is closed by the sealing contiguity of the secondseal 231 of second valve body 218 to the second sealing seat 232 ofinner cap component 214.

[0044] If the pressure inside the radiator increases to a certain pointabove the normal or ambient pressure, but below a first threshold valuefor pressure inside the radiator, the unscrew protection means ofpressure cap 211 is activated. As shown in FIG. 7, the radially innervalve body part 265 of first valve body 217 is moved upward, while thesecond valve body 218 remains in its sealing position. Furthermore, theradially outer valve body part 266 of first valve body 217 remains inits sealing position in relation to the second valve body 218. Themembrane annular seal 221 allows this relative movement between theradially inner valve body part 265 and the radially outer valve bodypart 266 because this seal has a meandering shape between its twosealing edges 267 and 268. As the radially inner valve body part 265moves outward in the direction of Arrow A, it carries along guidancesleeve 271 which in turn moves coupling insert 280 against the effect ofcompression spring 281 while its fingers 272 push the axiallyinward-directed claws 282 out of recesses 283 in locking element 210.This axial movement comes to an end when the inner shoulder of guidancesleeve 271 strikes against locking element 210. This disengagement ofcoupling element 280 from locking element 210 of outer cap component 213has the effect that handling element 212 idles in relation to lockingelement 210, such that starting at a predetermined overpressure (in thiscase, for example, 0.3 bar) pressure cap 211 can no longer be unscrewedfrom the radiator's neck.

[0045] If the pressure inside the radiator continues to rise, i.e. abovethe first predetermined first threshold value (such as 1.4 bar), valveassembly 215 reaches the operating state shown in FIG. 8 in which—due tothe increased pressure inside the radiator the radially outer sealingedge 268 of the first ring seal 221 of the radially outer valve bodypart 266 of first valve body 217 lifts against the effect of its firstcompression spring 222 off the first sealing seat 224 of second valvebody 218, thus opening the first flow connection 250, such that air fromthe air cushion above the liquid coolant can flow outside and thuscompensate or reduce the overpressure. Due to the overpressureprevailing in chamber 234, the second ring seal 213 of second valve body218 continues to be pressed against the second sealing seat 232 of innercap component 214. If this reduces the overpressure again below thefirst threshold value, the radially outer valve body part 266 againbecomes sealingly adjacent to second valve body 218. The anti-rotationmeans remains activated as before.

[0046] If on the other hand, the pressure inside the radiator continuesto rise even during or after the air cushion escapes, and if this causesliquid coolant to reach the underside of the second and third valve body218, 219, the fact that the annular gap 247 is very narrow causes theliquid coolant to back up at the entrance to annular gap 247 and thusdynamic pressure at the full-surface underside of third valve body 219.This dynamic pressure causes the axial movement of third valve body 219against the effect of its second compression spring 246, at whose endthe third sealing seat 243 of third valve body 219 adjoins the thirdring seal 239 of second valve body 218 and closes the first flowconnection 250 (see FIG. 9).

[0047] The closing of the first flow connection 250 between the secondand third valve body 218, 219 causes the pressure in chamber 234 to dropto a point below the said threshold value, such that the radially outervalve body part 266 of first valve body 217 is moved toward the secondvalve body 218 under the effect of the first compression spring 222.This state is also shown in FIG. 9. If the cooling of the vehicle'sradiator causes the pressure inside the radiator to drop and the liquidcoolant to return again, the third valve body 219 is returned under theeffect of its second compression spring 246, such that the first flowconnection 250 in this region is opened again, as shown in FIG. 6.

[0048] If on the other hand, the pressure inside the radiator continuesto rise and the threshold value that constitutes the upper safety limitis exceeded, the second valve body 218 is lifted against the pressure ofthe first compression spring 222 bearing on the radially outer valvebody part 266 of first valve body 217 is lifted off the second sealingseat 232 on inner cap component 214, such that the second flowconnection 251 is opened and the said overpressure can be reduced (seeFIG. 10). The anti-rotation means remains to be activated. This allowsthe said overpressure to be reduced via the second flow connection,after which the valve bodies can be returned via the different operatingstates by the different compression springs and coupling insert 280, asshown in FIG. 6.

[0049] If the lower claws 283 of coupling insert 280 are radially offsetin relation to recesses 274 in locking element 210, it is enough to turnhandling element 210 to bring claws 282 and recesses 273 to mesh again,such that the tightened compression spring 281 returns the couplingelement into the activated position against the direction indicated byArrow A.

[0050] Valve assembly 215 is returned to the initial position shown inFIG. 6 only when the pressure inside the radiator ranges between avacuum threshold value and a first overpressure threshold value. Suchpressure conditions prevail, for example, when a vehicle is parked for along period of time or when the vehicle is driven while the coolantinside the radiator is sufficiently cooled by the headwind and/or thefan. If the vehicle is parked after a long drive, the pressure may riseinside the radiator causing the contents of the radiator (air, water orwater vapour) to flow into valve assembly 215. If as a result of thisafter-heating effect, the coolant volume expands so much that it exceedsthe volume of the radiator, this would necessarily lead to a dischargeof coolant. This undesirable effect is prevented as described above whenthe valve assembly is in the operating state shown in FIG. 7 to 9. If inthis operating state, the pressure in the cooling system continues torise in an uncontrolled fashion, leakages and other detrimental effectsdue to excessive demands on the radiator and/or its hose connectionsmust be prevented. These effects are prevented through the second valvestep as shown in FIG. 4, where the radiator pressure is limited to apredetermined safety threshold value.

[0051] If there is a vacuum inside the radiator, and if this vacuumfalls below a predetermined vacuum threshold value, sealing seat 261 ofvacuum valve body 257 is lifted off the underside of the radially insidesealing edge 267 of the first ring seal 221 of first valve body 217toward the inside of the radiator. Vacuum pressure valve 257 is loweredagainst the bias of third compression spring 259, such that a flowconnection (not shown) is opened between the inside and the outside ofthe radiator.

1. Pressure cap (111, 211) for openings in tanks, in particular inautomobile radiators, with an outer cap component (110, 210) which isprovided with a locking element (113, 213) that can be connected to thetank's neck, and provided with a handling element (112, 212) rotatablymounted in relation to said locking element, with an anti-rotation meansprovided with coupling insert (180, 280) which is held non-rotatably inthe handling element (112, 212) and can be axially moved back and forth,for the releasable anti-rotational connection of the locking andhandling element, and with a valve assembly (115, 215) containing avalve body (117, 217) that can be axially moved back and forth, forreleasing and blocking flow connections between the inside and theoutside of the tank depending on predetermined values of the pressureprevailing inside the tank, characterized in that the axial engaging anddisengaging movement of the coupling insert (180, 280) is derived fromthe pressure-dependent axial movement of the valve body (117, 217) ofthe valve assembly (115, 215).
 2. Pressure cap according to claim 1,characterized in that between the valve body (117) and the couplinginsert (180) an axial first compression spring (183) is provided. 3.Pressure cap according to claim 1 or 2, characterized in that betweenthe valve body (117) and the coupling insert (180) a guidance element(147) is provided whose one end sits on the valve body (117) and whoseother end can be axially moved in relation to the coupling element (180)and engages in same.
 4. Pressure cap according to claims 2 and 3,characterized in that the axial first compression spring (183) is heldbetween the guidance element (147) and the coupling element (180). 5.Pressure cap according to claims 2 to 4, characterized in that theguidance element (147) is axially movable and can be coupled with thecoupling insert (180) in the direction of the effect of the firstcompression spring (183).
 6. Pressure cap according to claim 1 and atleast one of claims 3 to 5, characterized in that a second compressionspring (184) is provided between the guidance element (147) and theinner cap component (114).
 7. Pressure cap according to at least one ofthe previous Claims, characterized in that axially extending teeth areprovided on the outer circumference of the coupling insert (180) and onthe inner circumference of the locking element (113).
 8. Pressure capaccording to claim 1, characterized in that between the valve body (127)and the coupling insert (280) a movement-transmitting element (217) isprovided whose one end adjoins the valve body (217) and whose other endadjoins the coupling insert (280).
 9. Pressure cap according to claim 8,characterized in that the coupling element (280) and the end of themovement-transmitting element (217) which faces the former have mutuallyadjoining fingers (283, 272) which engage in axial recesses (273) of thelocking element (213).
 10. Pressure cap according to claim 8 or 9,characterized in that the coupling element (280) is acted upon by acompression spring (282) which is supported on the inside of thehandling element (212).